Hydraulic control of drill string tools

摘要

A drill string tool has a control mechanism to switch the tool between an inactive condition and an active condition in response to operator-performance of a predefined trigger sequence comprising variations in a drilling fluid pressure differential. The trigger sequence comprises multiple cycles of (a) raising the predefined trigger sequence into, but not above, a predefined pressure range, and (b) lowering the predefined trigger sequence below a lower threshold of the pressure range. Raising of the pressure difference above an upper pressure range threshold results in automatic interruption and resetting of the predefined trigger sequence.

主权项

1. An apparatus comprising:
a body configured for incorporation in a drill string to convey drilling fluid along an interior of the body; a control mechanism connected to the body and configured for coupling to a drill string tool to switch the drill string tool from an inactive condition to an active condition in response to occurrence of a predefined trigger sequence in variations in a fluid pressure differential between the interior and an exterior of the body, the predefined trigger sequence comprising multiple cycles of
increasing the fluid pressure differential into, but not above, a predefined intermediate pressure range, andsubsequently lowering the predefined trigger sequence below the predefined intermediate pressure range; wherein the control mechanism is further configured to be disposed between:
a repeat mode in which the drill string tool is again switched to the active condition upon raising of the fluid pressure differential above the predefined intermediate pressure range, without performance of the predefined trigger sequence; anda reset mode in which again switching the drill string tool to the active condition is conditional on performance of the predefined trigger sequence.